Telephone-exchange system.



c. w. KECKLER.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED JAN. 2'. 1918.

1,297,358. Patented Mar. 18,1919.

. 071 6/720/1 6/70/46: lZ/feck/er NITED STATES PATENT CHARLES W. KECKLER, OF NEVTARK, NEW JERSEY, ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

Specification of Letters Patent.

Patented Mar. 18, 1919.

Application filed January 2, 1918. Serial No. 209,972.

To all whom it may concern:

Be it known that 1, CHARLES W. Knox- LER, a citizen of the United States, residing at Newark, in the county of Essex, State of New Jersey, have invented certain new and useful Improvements in Telephone- Exchange Systems, of which the following is a full, clear, concise, and eXact description.

This invention relates to telephone systems and more particularly to such systems in which telephone lines of diflerent characters terminating at a central office may be interconnected indiscriminately by means of a universal link circuit.

The object of this invention is to provide a simple and inexpensive system of this character by means of which the work of the operator is simplified and the time required for completing connections between the subscribers lines is reduced.

In accordance with one feature of this invention, there is provided in a usual link or connecting circuit, alistening relay which automatically connects an operators telephone set with a calling line upon the connection of the link circuit therewith and which automatically disconnects such operators telephone set when the link circuit is connected with the called line, irrespective of the character of the calling or called lines.

This and other features not specifically mentioned above, may be fully understood from the following specification and the annexed drawing, in which is illustrated one embodiment of this invention.

In the accompanying drawing there is shown an ordinary common battery subscribers line A and a local battery subscribers line B terminating at a central oflice at which there is provided a universal cord circuit C for interconnecting the subscribers lines. For the sake of simplicity, only two such lines are shown, although it will be understood that a plurality of each of such classes of lines may terminate at the central oflice. The universal c'ord circuit C may be used indiscriminately to interconnect two local battery lines, two common battery lines or a local and a. common battery line.

All portions of the cord circuit C, unesplaced in series with the marginal relay 3 in the sleeve conductor of the answering portion of the cord circuit and winding 7 is similarly associated with marginal relay 8 in the sleeve conductor of the calling portion of the cord circuit, while the auxiliary or compensating winding 6 is connected between the armatures of the relays 3 and 8. Relays 3 and 8 are both adapted to operate when connected in series with the comparatively low resistance sleeve conductors of the common battery lines and to remain unoperated when connected in series with the comparatively high resistance sleeve conductors of the local battery lines. Windings 5 and 7 are of the same resistance and number of turns, while winding 6. has one half as many turns as winding 5 or 7 Windings 5 and 7 are connected in opposition, while the effect of winding 6 depends upon the positions occupied by the armatures of relays 3 and 8.

It is thought that the invention will be more fully understood from the following description of the operation of the system. 4

If it is desired to interconnect two local battery lines, the answering plug 1 is inserted in the jack of the calling magneto line, thereby operating the listening relay 4 and the cut-off relay associated with such line,

over a circuit proceeding from battery,

through winding 5 of relay 4, winding of marginal relay 3, sleeves of plug 1 and of the jack of the calling line, winding of cut-ofl relay (similar to cut-off relay 10 of line B) to ground. However, marginal relay 3 does not operate, due to thehigh resistance sleeve of the calling line. Listening relay 4;, in operating, associates the operators telephone set with the link circuit and thereby places the operator in communication with the calling subscriber. Upon being advised that the calling subscriber desires to converse with the subscriber on local battery line B, the operator inserts calling plug 9 in the jack of line B, whereby a circuit is established from battery, through winding 7 of listening relay at, winding of marginal relay 8, sleeves of plug 9 and of the jack of line B, winding of cut-off relay 10 to ground. As in the former case, cut-ofl relay 10 operates while marginal relay 8 will remain unoperated. Since the two connected lines have the same sleeve resistance, the resistance of the circuit just traced agrees with that of the similar circuit previously traced in connection with the answering portion of the cord circuit. Therefore, since the windings 5 and 7 containequal numbers of turns and are connected in opposition, relay 4 will release, disconnecting the operators telephone set from the cord circuit.

If two common battery lines are to be interconnected, the insertion of answering plug 1 in the jack of line A will complete a circuit extending from battery, through winding 5 of relay 4, winding of marginal relay 3, sleeves of plug 1 and of the jack of line A, winding of relay 2to ground. Relays 2 and 4 operate as before and, due to the low resistance sleeve of line A, marginalrelay 3 also operates, completing a circuit from battery, through alternate contact of relay 3, winding 6 of relay 4, normal contact of relay 8 to ground. Since the winding 6 has one half as many turns as winding 5 and is now connected in opposition thereto, the flux density in the core of relay 4 is reduced, due

to the current flowing in winding 6. Ascertaining that a connection with another common battery line isdesired, the operator in serts the calling plug 9in the jack of a common batteryline, and thereupon a circuit is established from battery, through winding 7 of relay 4, winding of marginal relay 8, sleeves of plug 9 and of the jack of the called common battery line, winding of the cut-off relay associated with such line (similar to relay 2 of line A) to ground. The cut-off relay of the called line thereupon operates and, due to the low resistance of -the sleeve circuit of such line, marginal relay 8 also operates, rendering winding 6 of relay 4 ineffective. The resistancesof the sleeve circuits including windings 5 and 7 being equal and such windings being connected in opposition, relay 4 releases, as in the former case, disconnecting the operators telephone set from the cord circuit.

In case a subscriber on a common battery line desires to converse with a subscriber on a local battery line, the calling plug 1, upon being'inserted in the jack of line A, completes a circuit from battery, through winding 5 of relay 4, winding of relay 3, sleeves of plug 1 and of the jack of line A, winding of cut-off relay 2 to ground. As previously described, relays 2, 3 and 4 operate, connecting the operators telephone set with the cord circuit and placing winding 6 of relay 4 in opposition to winding 5. Upon being advised that connection with line B is desired, the operator inserts calling plug 9 inthe jack of line B, establishing a circuit from battery, through winding 7 of relay 4, winding of marginal relay 8, sleeves of plug 9 and of the jack of line B, winding of cut-ofl" relay 10 to, ground. Relay 10 operates, but due to the high resistance sleeve of line B, relay 8 does not operate, and the amount of current the efi'ect of the current flowing through the V equalizing or balancing winding 6,, which also opposes that of winding 5, is suflicient to completely overcome the effect of winding 5 and to cause the release of relay 4, disconnecting the operators telephone set from the cord circuit. I,

In case a subscriber on alocal battery line desires to converse with the subscriber on'a common battery line, the operator inserts the answering plug 1 in the ack ofthe calling local'battery line, completing thereby a 'cirxcuit from battery, through winding '5 of relay 4, winding of relay 3, sleeves of plug 1 and of the jack of the calling line, winding of the cut-off relay (similar to relay 1d of line B) to ground. As previously described, listening relay 4 and the cut-off relay of the calling line operate, while marginal relay 3 does not operate. Upon being advised that a connection with a common battery line is desired, the operator inserts the callingplug 9 in the jack of the wanted comnion battery 7 line, establishing thereby a circuit fI'OFflbttttery, through winding 7 v of relay 4, winding of relay 8, sleeves of plug '9 and of. the jack to. ground. Since the resistance of the called line is comparatively low, the current flowing through winding 7 is considerably in excess of that flowing through theopposing winding 5 which is connected to the line having a high resistance sleeve. However, in this case, the current flowsthrough wind-v ing 6 in a different direction sothat it pro duces an effect in. opposition to that of the current in winding 7, and thecombined elfect produced by the currents in windingsv 6 and 7 exactly neutralizes the eflect produced by the current in winding 5, and relay 4is therer'ore released as before. v Y

It will thus be seen that the auxiliary or compensating winding 6 of relay 4 assists in the release of such relay whenever lines of different characters are interconnected, While such winding is not employed in case the interconnected lines are similiar .in character. It is also evident that either end of 1. A telephone exchange system comprising a plurality of common battery and local battery telephone lines, a link circuit for interconnectinglthe lines indiscriminately, an

oper'ators telephone set,'a diflerential relay having a winding associated with each end of the link circuit and operating when one end thereof is connected with a calling line of either character to connect the telephone set therewith, a compensating winding for the relay, and means in each end of the link circuit for renderng the compensating winding effective while the link circuit interconnects the lines of different characters, thereby releasing the relay to disconnect the telephone set.

2. A telephone exchange system comprising a plurality of common battery and local battery telephone lines, a link circuit for interconnecting the lines indiscriminately, an operators telephone set, a differential relay having a winding associated with each end of the link circuit and operating when one end thereof is connected with a calling line of either character to connect the telephone set therewith, a compensating winding for the relay, and a relay in each end of the link circuit for rendering the compensating winding eflective while the link circuit interconnects the lines of different characters, thereby releasing the relay to disconnect the telephone set.

3. A telephone exchange system comprising a plurality of common battery and local battery telephone lines, a link circuit for interconnecting the lines indiscriminately, an

operators telephone set, a differential relay having a winding associated with each end of the link circuit and operating when either end thereof is connected with a calling line of either character to connect the telephone set therewith, a compensating winding for the relay, and means in each end of the link circuit for rendering the compensating winding effective while the link circuit interconnects the lines of different characters, thereby releasing the relay to disconnect the telephone set.

4. A telephone exchange system comprising a plurality of common battery and local battery telephone lines, a link circuit for in terconnecting the lines indiscriminately, an operators telephone set, a differential relay having a winding associated with each end of the link circuit and operating when either end thereof is connected with a calling line of either character to connect the telephone set therewith, a compensating winding for the relay, and a relay in each end of the link circuit for rendering the compensating winding effective while the link circuit interconnects the lines of different characters, thereby releasing the relay to disconnect the telephone set.

5. A telephone exchange system comprising a plurality of common battery and local battery telephone lines, a link circuit for interconnecting the lines indiscriminately, an operators telephone set, a differential relay having a winding associated with each end of the link circuit and operating when one end thereof is connected with a calling line of either character to connect the telephone set therewith, a third winding for the relay for compensating for difference in ampere turns of the other two windings, switching means in each end of the link circuit, and a circuit for the third winding including contacts of both switchin means for rendering the third winding e ective while the link circuit interconnects the lines of different characters, thereby releasing the relay to disconnect the operators telephone set.

6. A telephone exchange system com rising a plurality of common battery and ocal battery telephone lines, a link circuit for interconnecting the lines indiscriminately, an operators telephone set, a differential relay having a winding associated with each end of the link circuit and operating when one end thereof is connected with a calling line of either character to connect the telephone set therewith, a compensating winding for the relay, a circuit for the compensating winding, and a relay in each end of the link circuit jointly controlling the circuit of the compensating winding to render the associated winding effective while the link circuit interconnects the lines of different characters, thereby releasing the relay to disconnect the operators telephone set.

7. A telephone exchange system comprising a plurality of common battery and local battery lines, a link circuit for interconnecting the lines indiscriminately, an operators telephone set, a differential relay having a winding associated with each end of the link circuit and operating when one end thereof is connected with a calling line of either character to connect the telephone set therewith, a compensating winding for the relay for compensating for difference in ampere turns of the other two windings, and means in each end of the link circuit cooperating to determine the direction of current flow through the compensating winding, thereby releasing the relay to disconnect the operators telephone set while the link circuit interconnects the lines of difierent characters.

8. A telephone exchange system comprising a plurality of common battery and local battery lines, a link circuit for interconnecting the lines indiscriminately, an operators telephone set, a differential relay having a winding associated with each end of the link circuit and operating when one end thereof is connected with a calling line of either character to connect the telephone set therewith, a compensating winding for the relay for compensating for difference in ampere turns of the other two windings, and a relay in each end of the link circuit cooperating to determine the direction of current flow through the compensating winding, thereby releasing the relay to disconnect the operators telephone set while the link circuit interconnects the lines of different characters.

' 9. VA telephone exchange system comprising a plurality of common battery and local battery telephone lines, a link circuit for interconnecting the lines indiscriminately, an operators telephone set, a differential relay having a winding associated with each end of the link circuit and operating when one end thereof is connected with a calling line of either character to connect the telephone set therewith and releasing when the link circuit interconnects lines of like character to disconnect the operators; telephone, a compensating winding for the relay adapted to aid either of the other windings in releasingv the relay when the link circuit interconnects the lines of diflerent characters," and means in each end of the link circuit cooperating to determine the winding to be aided.

10. A telephone exchange. system comprising a-plurality of commonbatteryiand local battery telephone lines, a link circuit for interconnecting the lines indiscriminately, an operators telephone set, a difierential relay having a winding associated with. each end of the link circuit andoperating'when one end thereof is connected with a calling" line of either character to connectthe telephone set therewith and releasing when the link circuit interconnects lines of like character to disconnect the operatorstelephone, a compensating winding for the relay adapted to aid either of the other windings in releasing the relay when the link circuit interconnects the lines of difierent characters, and a relay in each end of the-link circuit cooperating to determine the winding tobe aided.

In witness whereof, I hereunto; subscribe my name this 28th day of December, D.

-CHARLES W KECKLER.

vewcents each, by addressing the rcnmmissioner tonratenu, Washington, D, 0." v 

